Investigations of new potential photo-acid generators: crystal structures of 2-[(E)-2-phenyl­ethen­yl]phenol (ortho­rhom­bic polymorph) and (2E)-3-(2-bromo­phen­yl)-2-phenyl­prop-2-enoic acid

The title compounds, C14H12O, (I), and C15H11BrO2, (II), were prepared and characterized as part of our studies of potential new photo-acid generators. In (I), which crystallizes in the ortho­rhom­bic space group Pca21, compared to P21/n for the previously known monoclinic polymorph [Cornella & Martin (2013[Cornella, J. & Martin, R. (2013). Org. Lett. 15, 6298-6301.]). Org. Lett. 15, 6298–6301], the dihedral angle between the aromatic rings is 4.35 (6)° and the OH group is disordered over two sites in a 0.795 (3):0.205 (3) ratio. In the crystal of (I), mol­ecules are linked by O—H⋯π inter­actions involving both the major and minor –OH disorder components, generating [001] chains as part of the herringbone packing motif. The asymmetric unit of (II) contains two mol­ecules with similar conformations (weighted r.m.s. overlay fit = 0.183 Å). In the crystal of (II), both mol­ecules form carboxyl­ate inversion dimers linked by pairs of O—H⋯O hydrogen bonds, generating R22(8) loops in each case. The dimers are linked by pairs of C—H⋯O hydrogen bonds to form [010] chains.